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Brent Aebi, Peter Bracha, Thomas A Ciulla; Microbial Spectrum and Antibacterial Susceptibility of Vitreous Cultures in a Tertiary Referral Center in the Midwestern United States. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5500.
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Antibiotic resistance continues to worsen and concern has developed over resistance to vancomycin and ceftazidime in the empirical treatment of endophthalmitis. We performed a retrospective case series to investigate the microbial spectrum and susceptibility of vitreous cultures in endophthalmitis at a tertiary referral center in the Midwestern United States.
Microbiological identification and susceptibility results were obtained for endophthalmitis samples submitted to Indiana University between April 14, 2006 and April 14, 2016. The samples were submitted by 11 local vitreoretinal surgeons from 6 different sites within Indianapolis.
A total of 295 endophthalmitis vitreous specimens were processed. Of these, 96 (33%) samples grew an organism. Bacteria constituted 87.5% of identified organisms, with the remainder fungi. The most common organisms identified were coagulase negative Staphyloccocus (37.5%), Streptococcus viridans (7%), Enterococcus species (6%) and Staphylococcus aureus (6%). Among gram positive organisms, forty isolates of coagulase negative staphylococcus species, enterococcus species and Staphylococcus aureus underwent susceptibility testing, of which one hundred percent were susceptible to vancomycin. Thirty four of these gram positive isolates underwent susceptibility testing for rifampin and clindamycin, of which 100% and 76% were susceptible, respectively. Among gram negative organisms, seven isolates of Pseudomonas aeruginosa, Serratia marcescens and Pantoea agglomerans underwent susceptibility testing. Of these, 100% were susceptible to ceftazidime, cefepime, ciprofloxacin and levofloxacin. Susceptibility testing was not performed on beta-hemolytic streptococci, Haemophilus influenza, and Neisseria, Moraxella and Bacillus species.
This study, from a tertiary referral center in the Midwestern United States, shows a 100% susceptibility to the combination of vancomycin and ceftazidime in the bacterial isolates that were tested. Of note, all staphylococcal and enterococcal species were susceptible vancomycin. Limitations of this study include the large number of samples that did not undergo susceptibility testing. Despite these limitations, no evidence suggests that local resistance to vancomycin and ceftazidime has yet developed.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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